The invention relates to an explosive separation system for a variety of applications, and more particularly, to a reliable, clean operating and low cost separation joint made by an extrusion and rolling process. The extrusion process facilitates the manufacture of a single frangible joint member that replaces a pair of rings in prior art separation systems, thereby simplifying manufacture and assembly with the attendant cost savings. Explosive separation systems are most commonly used for stage and payload separation in various space applications.
Existing explosive separation joints are costly to manufacture. The primary sources of these costs are the precision machined rings they employ and the tedious assembly process required. For example, the explosive system disclosed in U.S. Pat. No. 3,698,281 requires the manufacture of two separate precision machined rings 50 and 52 (shown in cross section in FIG. 3). After manufacture, the rings 50 and 52 are attached to the two sections to be joined, 54 and 56. One ring 52 is attached to the interior portion of sections 54 and 56, while the other ring 50 is attached to the exterior portion of sections 54 and 56. Each ring 50 and 52 has a recess, which together form a hollow portion 58 to receive an explosive core when the rings are assembled. The placement of the rings 50 and 52 has to be performed with great accuracy to ensure that an explosive core within the hollow portion 58 is properly positioned to completely separate sections 54 and 56 after detonation. Each ring 50 and 52 also has a notch 60 in the side opposite the recess, along which the rings 50 and 52 separate upon detonation of the explosive core. The thickness of the material between each notch 60 and the explosive core 62 must be controlled precisely in order to ensure that the explosion of core 12 will cause complete separation around the entire circumference of rings 50 and 52.
Typically in the prior art, the ends of the tube containing the explosive core are sealed using a "swaging" process in which a round mandrel projecting from a block is pulled inside the tube. This causes the tube to flare to match the mandrel and results in a tight fit between the manifold and the tube. The explosive core extends completely through the mandrel and block via a bore. The block is then attached to the tube by welding. In prior art joints, while the majority of the tube length is oval, the ends are left round to facilitate the foregoing attachment. Thus, the manufacture of the prior art joint required precision machined rings and their meticulous assembly with the explosive core and attachment to the structures to be separated.
By contrast, the present invention employs a single-piece, hollow-form extrusion containing an explosive core, rather than two separate plates or rings (one on the inboard side and one on the outboard side of the explosive core). The process of forming and attaching a single extrusion joint avoids the need for precisely machining and attaching two separate rings, which can be up to several feet in diameter. The joint of the present invention also comprises a new manifold that facilitates sealing the ends of the extrusion and initiating detonation of the explosive core. Thus, the extruded frangible joint of the present invention is superior to prior art joints employed in explosive separation systems.